Download Live Streaming with Content Centric Networking

Live Streaming with Content Centric Networking
Hongfeng Xu2,3, Zhen Chen1,3, RuiChen2,3, Junwei Cao1,3
1
Research Institute of Information Technology
Department of Computer Science and Technology
3
Tsinghua National Laboratory for Information Science and Technology
Tsinghua University, Beijing 100084, China
Email: [email protected]
2
Abstract—Media streaming is the killer application in current
Internet.There are a variety of media streaming techniques in
today’s Internet, such as RTSP, HTTP live streaming and
Adobe Flash etc.HTTPlive streaming(HLS) is a popular and
most promising technique asthe protocol is based on the
Internet workhorse protocol i.e.HTTP, and supported by
HTML5 and mobile platform. Most of these media streaming
techniques are based on TCP/IP, which is built on the
traditional host-to-host network architecture. The host-to-host
architecture is proved to be inefficient in content distribution
with a lot of bandwidth waste, and it is complicated to deploy
network service because of TCP/IP’s location-dependence.
Content Centric Networking (CCN) is a future Internet
architecture which is targeted to solve the above problems by
location-independentcontent naming and universal content
caching in router. In this paper, we investigate both HTTP live
streaming and CCN, and propose a design of CCN live
streaming, which is a media streaming technique base on CCN.
Finally, we demo our CCN live streaming on Android client,
and conductevaluationexperiments.The results demonstrate
that the CCN live streaming is a low-cost scheme and much
easier to deploy and configure in operationcompared with
HTTP live streaming.
Keywords-Media Streaming; Content Centric Networking;
HTTP Live Streaming;Future Internet Architecture
I.
INTRODUCTION
The Internet has evolved to be concentrated on content
distribution. Especiallyin recentyears, with the rapid
development of access network bandwidth, most of the
content on the Internet exist as information-intensive form
like video or audio. According to theCisco Visual Network
Index[1], video content take 40 percent of all the Internet
content in 2010, and that will be 50 percent in 2012.
People’s real-time requirement of information retrieval
becomes more and more strong, this is why media streaming
techniques appear, and the growth of access
networkbandwidth also makes it possible. We can see media
streaming techniques everywhere on the Internet today,
online video, Internet radio, Internet TV and so on. However,
all these media streaming techniques are based on TCP/IP,
which is host-to-host architecture. Using the host-to-host
architecture in content distribution may lead to bandwidth
waste, because you have to get the content data really from
the server, even some hosts nearby may already got the data.
Secondly, TCP/IP is alocation-dependentprotocol [6], which
makes it complicated to deploy and configure network
service.HTTP live streaming[2,3] is one of these media
streaming techniques, which is based on HTTP protocol.
Content Centric Networking[4-6] is a future Internet
architecture. The core idea of CCN is named data, that
means user do not get content from the data’s location, but
the data’s name. This is a really significant improvement,
exchanging the content distribution from “where” to “what”.
It is important because most action of today’s Internet is
content distribution, and the users do not care where the data
is, but what the data is. Named data architecture make the
network easy to cache content, actually we can say that CCN
is natively support content caching. Additionally, because
named data make CCN location-independent, network
service can be much easier to deploy and configure in CCN.
In this paper, we propose a design of CCN live streaming.
CCN live streaming splits the video into a sequence of
segments, and generates a playlist file, asHTTP live
streaming do. The user who wants to play this video
streaming can download the small playlist file, andplay the
video by getting the video segments one by one. All the file
delivery is using CCN protocol, instead of HTTP. The last
section of this paper contains some experiments that prove
CCN live streaming is more efficient and flexible than HTTP
live streaming on content distribution.
II.
HTTP LIVE STREAMING
A. Introduction to HTTP Live Streaming
Live streaming is technique that the end-user can play the
video of an event as it happens, that means the video data is
still transmitting or even generating. One of the most widely
used live streaming technique is HTTP based live streaming,
which implemented by Apple Inc.[3]
HTTP live streaming works by splitting the overall video
streaming into a sequence of small HTTP-based downloads.
Figure 1 is the architecture of HTTP Live Streaming given
by the web site of Apple.
Figure 1. Structure of HTTP Live StreamingSystem[3]
The media encoder will encode the original audio or
video into MPEG-2 stream, and the stream segmenter will
break the stream into a sequence of stream segments (ts file),
and also generate the playlist which store in the index file
(m3u8 file). At the start of the streaming session, the client
application will download the index file first, and then start
to download the segment files by analyzing the index file, all
these data transmitting are using HTTP protocol. The HTTP
Live Streaming protocol details can be found in IETF draft
[2].
B. Disavantages of HTTP Live Streaming
1) Availability
The HTTP live streaming technique relies on the
traditional host-to-host network model, and is a client-server
architecture. As we know, one advantage of the host-to-host
model is that, if the client-end wants some data from the
server-end, then the client’s requests have to go through the
whole network between them and arrive the server-end, then
the server-end will send the data back. That means, when
you want to watch a live video on the Internet, you have to
get the video stream really from the video server, even that
your roommate is watching that video too, and actually he
has already download some parts of the video stream.
Obviously, this will waste much bandwidth, and make the
Internet overwhelmed.
2) Location-dependence
The communication in HTTP live streaming is host-tohost, because the underlying implementation is TCP-IP. That
means if you want to watch a live video, you should know
the IP address of the video server. The host-to-host network
architecture was introduced to fit the problems of the ‘60s.
However, today’s Internet has evolved to be dominated by
content distribution and retrieval. The users of Internet do
not care where the contentis, but what the content is.
Mapping content to host locations makes the network
services complicated to implement and configure.
III.
CONTENT-CENTRIC NETWORKING
A. Introduction to CCN
Content-centric networking is a future Internet
architecture, which founding principle is that Internet should
allow users to get data by the data’s name, instead of the
data’s physical location. Just like TCP/IP, CCN network
stack is a thin-waist model, too. However, the thin waist
part in CCN is a content chunks instead of IP layer. In the
view of network, this means that CCN index data from the
data’s name but not the physical location. In IP network, the
users request data by giving the destination IP. In CCN, the
users send a request called Interest which contains the data’s
name. Additionally, CCN can be layered over everything,
even layered over IP. Everything over named data, and
named data over everything.
There are two package types in CCN, Interest and Data.
The consumer node requests a named data by sending an
Interest, which contains the name of the data. Any node that
got the Interest can respond the Interest and send the named
data back if it has already got the data. The node that
responds the Interest may be the producer node, or the
middle CCN router node which is caching the data.
Figure 2 is the forwarding model of CCN. Content Store
and Pending Interest Table (PIT) are the two components
that implements CCN content caching. For content store, it
is easy to understand, the CCN router will cache data in it
when a new data arrives. For the PIT, it will keep the
Interest which sending by this router and still on the way.
When a new Interest arrives, the router will firstlycheck the
Content Store.If the named data exists,the router willsend
this databack to the link where the Interest comes. If the
data cannot found in Content Store, the router will check the
PIT, if the same pending Interest exists, then add a new item
in PIT which records the Interest and the face which the
Interest come from. So when the data arrives, the router will
check all the items in PIT and forward the data to all of
those faces. If the Interest does not match the Content Store
and the PIT, then the router will forward the Interest
according the FIB, and also add an item in PIT. This is
almost how the CCN content caching works.
Figure 2. CCN Router Forwarding Model
B. Advantages of CCN
1) Content Caching
CCN natively supports content caching. The named data
model of CCN makes the CCN router very easy and natural
to cache data that go through the router. Every CCN router
has a component called content store which can cache the
data, and a Pending-Interest-Table which can remember the
Interest history. When a new Interest arrives, the CCN
router searches the content store first, if the data not exists
then search the PIT. A same interest exists in the PIT means
that there is someone sends an interest before but the data is
still on the way, so the router will not forward the interest
again. This content caching mechanism of CCN can
effectively reduce the network latency and bandwidth cost.
2) Location-independence
As we know, TCP/IP network architecture is locationdependent, which makes Internet service complicated to
implement and configure. CCN based on named data, not
the physical location. CCN protocols do not contain any
location information, so it is easy for Internet application to
deploy and configure their services.
IV.
CCN LIVE STREAMING
A. Introduction
We mentioned above that HTTP live streaming has some
disadvantages because it relies on session mechanism of
TCP/IP, and we also mentioned some advantages of CCN.
In this paper, we want to introduce CCN live streaming. In
CCN live streaming, client requests video stream by sending
CCN interest, and get the response data using CCN protocol
instead of HTTP.
B. Advantages of CCN Live Streaming
Obviously, CCN live streaming can benefit from the
content caching mechanism of CCN. Again, we take the
same example that mentioned at the start of this paper,
imagine that you want to watch a live video, at the same
time your roommate is watching that video too, and your
computers connect to the same router which is a CCN one.
If your video process is later than your roommate, then the
video stream segments are already cached in the router. Or,
if your process are almost same with your roommate, then
the router will only forward one interest to the Internet
because the pending mechanism of CCN, this can reduce the
network congestion and improve the video stream’s delivery
speed.
Additionally, for the live streaming provider, CCN live
streaming is much easier to implement and configure,
because of its location-independence. Current CCN
implementation ccnx is based on overlay network. Our CCN
live streaming can effectively leverage the overlay routing
to detect and adapt the underlay congested path quickly and
maintain the continuous service as suggested in RON[10]
and CORS[11]. Li Tang and Hui Zhang et al. also have
analyzed the benefits and the feasibility to improve the Endto-End QoS in [12-13].Yin Chen et al. propose an easy-tofollow overlay path selection algorithm in [14].
C. Implementation
We implement a CCN live streaming demo based on the
ccnx project[7-9].Before talking about the implementation
details, we should introduce some proper names in the ccnx
project.
 ccnd, it is a CCN routing daemon. Each CCN node
should run its own ccnd.
 ccn-repo, it is a CCN based application, which is a
repository that can store CCN data.
The demo includes a live streaming service on Linux
platform (as shown in Figure 3) and client software on
Android (as shown in Figure 4).
1) Server-end Architecture
As show in Figure 3, we are running a ccnd and a ccn
repository in the server-end. Just like HTTP live streaming,
first we break the input video into a sequence of segments,
and also generate an index file, which is actually a playlist.
Then we put all the files in the repository using the
ccnputfile tool given by ccnx project.
2) CCN name model design
Actually, outname model design is quite simple. Our
server is in the CCN name space ccnx://ccn.tsinghua.edu.cn.
So, if Bob is one of our users, he uploads a video named
clock.avi, and then the server will generate an index file
named clock.m3u8 in the CCN name space
ccnx://ccn.tsinghua.edu.cn/bob/clock.m3u8. And all the
segment files are in the name space like
ccnx://ccn.tsinghua.edu/cn/bob/clock/block1.ts.
Figure 3. Server-end Architecture
3) Client-end Architecture
We implement a client software base on Android
platform. Just like the server-end, we run a ccnd on the
client. The software includes a media player on Android,
which supports HTTP live streaming. The HTTP proxy is
the core component, which translates the HTTP request of
the media player into CCN interest, then the ccnd will
forward the interest. When the CCN response arrives the
ccnd, the ccnd will send the CCN response to the HTTP
proxy, and the proxy will translate the CCN response into
HTTP response and send it back to the media player.
Figure 4. Client-end Architecture
V.
EXPERIMENTS
A. Experiments Design
We design and implement a CCN live streaming
application as part of the project Omedia. Omedia is a CCN
project of Tsinghua NSLab, which is a CCN content
delivery system based on social network. Figure 5 shows the
Android client implementation and UI of Omedia.
flexibility as the routing is based on IP route. CCN overlay
routing is easy to configure to use a new overlay path.
Actually, CCN has a strategy layer which can do this work.
This experiment will measure the bandwidth when the client
chooses the different path.
Figure 5. Android Client Implementation
We conduct two kinds of experiments with Omedia. As
show in Figure 6, thefirst experiment is designed to
demonstrate that CCN can reduce the network load as the
number of simultaneous watch clients increased. All the
Android clients are tested in the Tsinghua campus network,
and connect to Internet through a CCN router. First, all the
clients will play the same video at the same time using both
CCN live streaming and HTTP live streaming, then measure
the network bandwidth consumption and video buffer delay
respectively. This can show the function of the pending
mechanism in CCN when content caching. Secondly, the
clients will play the video one by one, this will show the
function of the content store in CCN when content caching.
Figure 7. Overlay path selectionin live streaming with CCN
B. Experiment Results Analysis
As show in Figure 8, from the experiment results we can
see that, as the number of clients increasing, the network
load will get worse and worse if using HTTP live streaming.
CCN can make this condition much better because of
content caching.
Figure 6. Android Omedia clients retrive video content
Another experiment, shown in Figure 7, is to demonstrate
that CCN live streaming can be much easier to deployed and
configured. Location-dependence makes TCP/IP routing
complicated to configure, or worse, the service provider
may even not able to configure the routing because it can
only be configured by ISP. Take the path selection for
example, the client which using HTTPmay choose
anunsatisfied default routing path; even that path
experiencesserve loss ratio and bad latency. Hence, overlay
routing tobypass the bad link or router may gain a better
performance,whileHTTPLive Streamingwill not offer such
Figure 8. The media buffer delay in playingvideo simutaneously with lots
of Omedia clients
Figure 9 shows the condition that clients play the
video one by one, then most of the clients except the first
one can have a much better network bandwidth and delay.
distribution, and also makes the streaming service
complicated to deploy and configure. This paper proposes
CCN live streaming, which is a media streaming technique
base on Content Centric Networking. CCN live Streaming is
easy for content caching, and overcome the locationdependent problem. We demonstrate and evaluate a CCN
live streaming implementation basedon CCN overlaytestbed
and Android Omediaclient, and the experiments show that
CCN live streaming is low-cost for video distribution and
much easier for streaming service to deploy and configure.
VII. ACKNOWLEDGMENT
This work is supported by Ministry of Science and
Technology of China under National 973 Basic Research
Program
Grant
No.
2011CD302600,
Grant
No.2011CB302805 and China NSFC A3 Program
(No.61161140320).
VIII. REFFERENCES
[1]
[2]
[3]
[4]
[5]
Figure 9. The media buffer delayin playingvideo one by one with
OmediaClients
[6]
Figure 10 is the results of the experiment describes in Figure
7. The results show that CCN live streaming can easily
configure a routing path that bring a better network
bandwidth.
[7]
[8]
[9]
[10]
[11]
[12]
[13]
[14]
Figure 10. Achieveable network bandwidth withdifferent CCN overlay
path
VI.
CONCLUSION
Traditional media streaming techniques like HTTP live
streaming are based onTCP/IP which is built on host-to-host
network model.This model is inefficient in content
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